WO2021235150A1

WO2021235150A1 - Noise filter and power conversion device

Info

Publication number: WO2021235150A1
Application number: PCT/JP2021/015819
Authority: WO
Inventors: 斉谷口; 裕樹船戸
Original assignee: 株式会社日立製作所
Priority date: 2020-05-20
Filing date: 2021-04-19
Publication date: 2021-11-25
Also published as: DE112021001283T5; JP2021182841A

Abstract

A noise filter that suppresses noise superimposed on a current comprises: a plurality of busbars in which the current flows; a busbar support part that supports the plurality of busbars; and an insulation layer positioned between each of the plurality of busbars and the busbar support part, the busbar support part being a conductor, the busbars each having an embedded part embedded in the busbar support part, and the embedded parts being electrically insulated from the busbar support part.

Description

Noise filter, power converter

The present invention relates to a noise filter that suppresses noise superimposed on an electric current and a power conversion device using the noise filter.

Patent Document 1 is known as a background technique for the present invention. Patent Document 1 includes a core member, a positive electrode side conductor and a negative electrode side conductor penetrating the core member with their main surfaces facing each other, and a base for accommodating these, and the positive electrode side conductor and the negative electrode side conductor are provided. A noise filter circuit of a power converter arranged on a base via an insulating member is disclosed.

International Publication No. 2019/068433

With the technique of Patent Document 1, it is difficult to sufficiently dissipate heat generated by the core member due to noise suppression, and in order to maintain the filter performance, the noise level applied to the core member is limited to a certain value or less. There is a need. Therefore, there is room for improvement in terms of noise suppression.

The noise filter according to the present invention suppresses noise superimposed on a current, and includes a plurality of bus bars through which the current flows, a bus bar support portion that supports the plurality of bus bars, and the plurality of bus bars and the bus bar support. The bus bar support portion is a conductor, the bus bar has an embedded portion embedded in the bus bar support portion, and the embedded portion is provided with an insulating layer arranged between the portions. , Is electrically isolated from the bus bar support.
The power conversion device according to the present invention includes a noise filter, a power module, a smoothing capacitor for smoothing DC power, and a control unit for controlling the power module.

According to the present invention, it is possible to provide a noise filter capable of sufficiently suppressing noise and a power conversion device using the noise filter.
Issues, configurations and effects other than those described above will be clarified by the following description of embodiments for carrying out the invention.

It is external perspective view of the noise filter which concerns on 1st Embodiment of this invention. It is sectional drawing of the noise filter which concerns on 1st Embodiment of this invention. It is explanatory drawing of the current path through which a common mode noise current flows. It is external perspective view of the noise filter which concerns on a comparative example. It is explanatory drawing of the reduction effect of the common mode noise current by the noise filter which concerns on a comparative example. It is a figure which shows an example of the calculation result of the common mode noise current in the noise filter which concerns on a comparative example. It is explanatory drawing of the common mode noise current reduction effect by the noise filter which concerns on 1st Embodiment of this invention. It is a figure which shows an example of the calculation result of the common mode noise current in the noise filter which concerns on 1st Embodiment of this invention. It is a figure which shows the relationship between the capacitance value of the noise filter which concerns on 1st Embodiment of this invention, and a switching loss. It is external perspective view of the noise filter which concerns on 2nd Embodiment of this invention. It is sectional drawing of the noise filter which concerns on 2nd Embodiment of this invention. It is explanatory drawing of the common mode noise current reduction effect by the noise filter which concerns on 2nd Embodiment of this invention. It is sectional drawing of the noise filter which concerns on the modification of this invention. It is a block diagram of the noise filter which concerns on 3rd Embodiment of this invention. It is a block diagram of the noise filter which concerns on 4th Embodiment of this invention. It is a block diagram of the motor drive system which includes the power conversion apparatus which concerns on 6th Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and are appropriately omitted and simplified for the sake of clarification of the description. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range and the like disclosed in the drawings.

If there are multiple components with the same or similar functions, the same code may be described with different subscripts. However, if it is not necessary to distinguish between these multiple components, the subscripts may be omitted for explanation.

(First Embodiment)
The structure of the noise filter according to the first embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is an external perspective view of a noise filter according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the noise filter according to the first embodiment of the present invention.

As shown in FIG. 1, the noise filter 1 of the present embodiment includes a magnetic core 11, a plurality of bus bars 12, a base section 13 and a bus bar support section 14. Each bus bar 12 is configured by using a plate-shaped conductor, for example, a metal such as copper, and penetrates the magnetic core 11. The magnetic core 11 is configured by using a magnetic material such as a magnet, and has a through hole at the center for passing the bus bar 12 through. The bus bar support portion 14 is arranged on the base portion 13 and supports each bus bar 12.

In the example of FIG. 1, three bus bars 12 are shown, and each bus bar 12 is electrically connected to each of the U-phase, V-phase, and W-phase coils of the three-phase AC motor. That is, the U-phase current, the V-phase current, and the W-phase current of the three-phase AC motor flow through the three buses 12 of the noise filter 1, respectively. The noise filter 1 suppresses noise superimposed on these currents flowing through each bus bar 12. However, the number of bus bars 12 is not limited to three. An arbitrary number of bus bars 12 can be provided according to the number of phases of the current to be suppressed by the noise filter 1.

2 (a) is a cross-sectional view of the noise filter 1 in the line AA'shown in FIG. 1, and FIG. 2 (b) is a cross-sectional view of the noise filter 1 in the line BB'shown in FIG. It is a figure. As shown in FIG. 2, the bus bar 12 has a supported portion 122 supported by the bus bar support portion 14 between one end portion 121 and the other end portion 124, and a penetration portion 123 penetrating the magnetic core 11. And have.

At both ends of the supported portion 122 in a direction orthogonal to the extending direction of the bus bar 12 (horizontal direction in FIG. 2A) (horizontal direction in FIG. 2B), along the extending direction of the bus bar 12. A pair of embedded portions 125 formed by bending the bus bar 12 are provided. As shown in FIG. 2B, the embedded portion 125 is embedded in the Basba support portion 14 from the surface side to the inside of the Basba support portion 14.

The base portion 13 and the bass bar support portion 14 are each configured by using a conductor and are electrically grounded. An insulating layer 15 is arranged between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14. As a result, the supported portion 122 and the embedded portion 125 are electrically insulated from the bass bar support portion 14, and a parasitic capacitance component is formed between the supported portion 122 and the embedded portion 125 and the bass bar support portion 14. It has become so. The base portion 13 and the bus bar support portion 14 may be a part of a housing for accommodating the noise filter 1, or a part of the housing included in a device such as a power conversion device on which the noise filter 1 is mounted. May be. Further, the base portion 13 may be made of a non-conductive substance, and only the bus bar support portion 14 may be electrically grounded. In addition to this, any configuration is desired as long as at least the bus bar support portion 14 is electrically grounded and a parasitic capacitance component is formed between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14. Can be configured as.

Next, the common mode noise to be suppressed by the noise filter 1 will be described.

FIG. 3 is an explanatory diagram of a current path through which a common mode noise current flows. In FIG. 3, the power module 401 that outputs a three-phase alternating current and the electric motor 408 that is driven by receiving the supply of the three-phase alternating current from the power module 401 are an AC bus bar 403, an AC noise filter 404, an AC bus bar 405, and an AC. They are connected to each other via cable 406 and show the current path when a common mode noise current flows between them.

The common mode noise current generated by the common mode noise source 402 in the power module 401 is superimposed on the three-phase alternating current output by the power module 401. The three-phase alternating current on which the common mode noise current is superimposed flows into the motor 408 via the AC bus bar 403, the AC noise filter 404, the AC bus bar 405, and the AC cable 406.

A ground wiring 410 is commonly connected to the frame ground of the power module 401 and the motor 408, and each is electrically grounded via the ground wiring 410. Here, in the electric motor 408, the parasitic capacitance component 409 exists between the winding 407 and the frame ground, and in the power module 401, the parasitic capacitance component 411 exists between the common mode noise source 402 and the frame ground. It is assumed that you are doing. In this case, a loop current path is formed from the common mode noise source 402 to the common mode noise source 402 via the parasitic capacitance component 409 of the electric motor 408 and the parasitic capacitance component 411 of the power module 401. A common mode noise current 412 flows between the power module 401 and the motor 408 through this loop current path.

The noise filter 1 of the present embodiment has the above-mentioned structure and thus suppresses the common mode noise current generated as described above.

Subsequently, the effect of reducing the common mode noise current by the noise filter 1 of the present embodiment will be described below in comparison with the comparative example shown in FIG.

FIG. 4 is an external perspective view of the noise filter according to the comparative example. Compared to the noise filter 1 according to the first embodiment of the present invention, the noise filter 1C shown in FIG. 4 is not provided with the bus bar support portion 14 shown in FIGS. 1 and 2, and each bus bar 12C supports the bus bar. The difference is that it is not supported by part 14. Therefore, each bus bar 12C of the noise filter 1C has a plate-like shape as shown in FIG. 4, and the supported portion 122 and the embedded portion 125 shown in FIG. 2 are not provided in the bus bar 12C.

FIG. 5 is an explanatory diagram of the effect of reducing the common mode noise current by the noise filter 1C according to the comparative example. In FIG. 5, the common mode noise current 502 output from the common mode noise current source 501 in the power module flows into the bus bar 12C. A parasitic capacitance component 503 is formed between the bass bar 12C and the base portion 13. On the other hand, a parasitic capacitance component 504 is formed between the motor and the power supply connected to the power module via the bus bar 12C and the ground wire. Therefore, the common mode noise current 502 that has flowed into the bus bar 12C is divided into a current path that passes through the parasitic capacitance component 503 and a current path that passes through the parasitic capacitance component 504, flows into the ground line, and is common via the ground line. Return to the mode noise current source 501.

Here, in the structure of the noise filter 1C shown in FIG. 4, the parasitic capacitance component 503 formed between the bus bar 12C and the base portion 13 has a sufficiently small capacitance value as compared with the parasitic capacitance component 504. For example, in the three bus bars 12C provided corresponding to the three-phase alternating current, the capacitance value of the parasitic capacitance component 503 is about 10.5 pF in total for the three phases, whereas the capacitance value of the parasitic capacitance component 504 is a number. It is about nF. Therefore, the common mode noise current flowing through the parasitic capacitance component 503 is so small that it can be ignored, and almost all of the common mode noise current 502 flowing from the common mode noise current source 501 into the bus bar 12C passes through the magnetic core 11.

FIG. 6 is a diagram showing an example of the calculation result of the common mode noise current in the noise filter 1C according to the comparative example. FIG. 6 shows the result of calculating the common mode noise current by simulation when an in-vehicle motor for an automobile having a maximum output of about 100 kW is connected. The calculation result of FIG. 6 shows that a common mode noise current having an effective value of about 7.9 A is generated in the current flowing from the power module to the motor.

When the current on which the common mode noise current is superimposed as shown in FIG. 6 flows through the bus bar 12C and penetrates the magnetic core 11 of the noise filter 1C, the core loss generated in the magnetic core 11 reaches about several tens of watts. Therefore, the heat generated by the magnetic core 11 becomes large, which may cause deterioration of the filter performance or burning due to the excess of the Curie temperature. It is conceivable to avoid such a problem by enhancing the heat dissipation of the magnetic core 11, but in that case, it becomes a factor of cost increase due to the complicated structure.

FIG. 7 is an explanatory diagram of the effect of reducing the common mode noise current by the noise filter 1 according to the first embodiment of the present invention. In FIG. 7, the common mode noise current 502 output from the common mode noise current source 501 in the power module flows into the bus bar 12. In the noise filter 1, as described above, the parasitic capacitance component 603 is formed between the supported portion 122, the embedded portion 125, and the bus bar support portion 14. Therefore, the common mode noise current 502 flowing into the bus bar 12 is divided into a current path passing through the parasitic capacitance component 603 and a current path passing through the parasitic capacitance component 504, and flows into the ground line, respectively, and is common via the ground line. Return to the mode noise current source 501.

In the structure of the noise filter 1 shown in FIGS. 1 and 2, the parasitic capacitance component 603 formed between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14 is different from the parasitic capacitance component 503 in the comparative example. Unlike, it has a non-negligible capacitance value compared to the parasitic capacitance component 504. For example, in the three bus bars 12 provided corresponding to the three-phase alternating current, the capacitance value of the parasitic capacitance component 603 is about 7.8 nF in total of the three phases, and the capacitance value of the parasitic capacitance component 504 (for example, several nF). It is about the same. Therefore, the common mode noise current 502 from the common mode noise current source 501 flows separately in the current path passing through the parasitic capacitance component 603 and the current path passing through the parasitic capacitance component 504, and penetrates the magnetic core 11. Common mode noise current is greatly reduced. As a result, the heat generation of the magnetic core 11 can be suppressed as compared with the noise filter 1C according to the comparative example.

FIG. 8 is a diagram showing an example of a calculation result of a common mode noise current in the noise filter 1 according to the first embodiment of the present invention. FIG. 8 shows the result of calculating the common mode noise current by simulation when an in-vehicle motor for an automobile having a maximum output of about 100 kW is connected, as in FIG. 6 described above. The calculation result of FIG. 8 shows that a common mode noise current having an effective value of about 2.0 A is generated in the current flowing from the power module to the motor. From this, it can be seen that when the noise filter 1 of the present embodiment is used, the common mode noise current can be reduced to about 1/4 in effective value as compared with the noise filter 1C according to the comparative example.

As described above, according to the noise filter 1 of the present embodiment, the effect of suppressing the common mode noise and reducing the heat generation of the magnetic core 11 can be confirmed.

When the noise filter 1 of the present embodiment is applied to the AC filter and used for suppressing the common mode noise current superimposed on the three-phase alternating current output from the power module to the motor as shown in FIG. 7, the supported portion. The parasitic capacitance component 603 formed between the 122 and the embedded portion 125 and the bus bar support portion 14 becomes a capacitive load when viewed from the power module. Since this causes an increase in switching loss in the power module, it is preferable that the capacitance value of the parasitic capacitance component 603 is not too large.

FIG. 9 is a diagram showing the relationship between the capacitance value of the noise filter 1 and the switching loss according to the first embodiment of the present invention. In FIG. 9, the horizontal axis of the graph represents the capacitance value of the parasitic capacitance component 603 formed between the supported portion 122 and the embedded portion 125 of the noise filter 1 and the bus bar support portion 14, and the vertical axis of the graph is the power. It represents the rate of increase in switching loss of the module. The graph of FIG. 9 shows an example of the result of calculating these relationships by simulation.

In the noise filter 1, the larger the capacitance value of the parasitic capacitance component 603, the better the effect of suppressing the common mode noise current. On the other hand, as can be seen from the graph of FIG. 9, as the capacitance value of the parasitic capacitance component 603 increases, the switching loss increases. That is, in the noise filter 1, there is a trade-off relationship between suppression of common mode noise current and reduction of switching loss, and it is necessary to optimize these.

As described above, when the capacitance value of the parasitic capacitance component 603 is 7.8 nF (2.6 nF per phase) in total for the three phases, it can be seen from FIG. 9 that the increase rate of the switching loss is 0.9%, which is negligible. .. For example, in the power module of an inverter used in combination with an in-vehicle motor for automobiles, in order to suppress the increase rate of switching loss due to the noise filter 1 to about 5%, the capacitance value of the parasitic capacitance component 603 is set to 3 from FIG. It is desirable that the total number of phases is 25.5 nF (8.5 nF per phase) or less. On the other hand, in order to sufficiently obtain the effect of suppressing the common mode noise current, it is necessary to set the capacitance value of the parasitic capacitance component 603 to be about the same as the parasitic capacitance component 504 of FIG. 7 between the motor and the ground wire. For that purpose, for example, it is desirable that the capacitance value of the parasitic capacitance component 603 is 1 nF or more per phase.

As described above, in the noise filter 1 of the present embodiment, it is preferable that a capacitance of 1 nF or more and 8.5 nF or less is formed between each bus bar 12 and the bus bar support portion 14, respectively.

In the noise filter 1C of the comparative example shown in FIG. 4, in order to obtain the same effect as the noise filter 1 of the present embodiment, it is conceivable to arrange a Y capacitor between each bus bar 12C and the base portion 13. .. However, when such a structure is adopted, ESL (Equivalent Series Inductance) and ESR (Equivalent Series Resistance) are generated due to the lead wire of the Y capacitor, and the effect of suppressing the common mode noise current is reduced in the high frequency region. There is a risk of In addition, the addition of the Y-capacitor will increase the cost of materials, and the man-hours for screwing and welding to electrically connect the Y-capacitor between the bus bar 12C and the base portion 13 will increase, which may cause an increase in cost. Become. On the other hand, the noise filter 1 of the present embodiment is more advantageous than the addition of the Y capacitor because these problems do not occur.

According to the first embodiment of the present invention described above, the following effects are exhibited.

(1) The noise filter 1 suppresses noise superimposed on a current, and has a plurality of bus bars 12 through which a current flows, a bus bar support portion 14 that supports the plurality of bus bars 12, and a plurality of bus bars 12 and a bus bar. An insulating layer 15 is provided between the support portions 14. The bus bar support portion 14 is a conductor, the bus bar 12 has an embedded portion 125 embedded in the bus bar support portion 14, and the embedded portion 125 is electrically insulated from the bus bar support portion 14. Since this is done, it is possible to provide a noise filter capable of sufficiently suppressing noise.

(2) The noise filter 1 includes a magnetic core 11, and the plurality of bus bars 12 each penetrate the magnetic core 11 at the penetrating portion 123. Since this is done, the noise superimposed on the current flowing through the bus bar 12 can be further suppressed.

(3) It is preferable that a capacity of 1 nF or more and 8.5 nF or less is formed between the plurality of bus bars 12 and the bus bar support portion 14, respectively. By doing so, it is possible to realize an AC filter that optimizes the suppression of noise current and the reduction of switching loss, which are in a trade-off relationship.

(Second embodiment)
The structure of the noise filter according to the second embodiment of the present invention will be described below with reference to FIGS. 10 and 11. FIG. 10 is an external perspective view of the noise filter according to the second embodiment of the present invention. FIG. 11 is a cross-sectional view of the noise filter according to the second embodiment of the present invention.

As shown in FIG. 10, the noise filter 1A of the present embodiment includes a plurality of bus bars 12, a base section 13, and a bus bar support section 14. The noise filter 1A of the present embodiment is different from the noise filter 1 of the first embodiment described with reference to FIGS. 1 and 2 in that the magnetic core 11 is not provided. Other than this, the noise filter 1A of the present embodiment and the noise filter 1 of the first embodiment have the same structure. In this embodiment as well, as in the first embodiment, the number of bus bars 12 included in the noise filter 1A is not limited to three. An arbitrary number of bus bars 12 can be provided according to the number of phases of the current to be suppressed by the noise filter 1A.

11 (a) is a cross-sectional view of the noise filter 1A in the line AA'shown in FIG. 10, and FIG. 11 (b) is a cross-sectional view of the noise filter 1A in the line BB'shown in FIG. It is a figure. As shown in FIG. 11, the bus bar 12 has a supported portion 122 supported by the bus bar support portion 14 between one end portion 121 and the other end portion 124. Similar to the noise filter 1 of the first embodiment, in the supported portion 122, the direction orthogonal to the extending direction (horizontal direction in FIG. 11A) of the bus bar 12 (horizontal direction in FIG. 11B). A pair of embedded portions 125 formed by bending the bus bar 12 along the extending direction of the bus bar 12 are provided at both ends. The embedded portion 125 is embedded in the bass bar support portion 14 from the surface side to the inside of the bass bar support portion 14.

An insulating layer 15 is arranged between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14. As a result, the supported portion 122 and the embedded portion 125 are electrically insulated from the bass bar support portion 14, and a parasitic capacitance component is formed between the supported portion 122 and the embedded portion 125 and the bass bar support portion 14. It has become so. Any configuration is used as long as at least the bus bar support portion 14 is electrically grounded and a parasitic capacitance component is formed between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14. can do.

FIG. 12 is an explanatory diagram of the effect of reducing the common mode noise current by the noise filter 1A according to the second embodiment of the present invention. In FIG. 12, the common mode noise current 502 output from the common mode noise current source 501 in the power module flows into the bus bar 12. In the noise filter 1A, the parasitic capacitance component 603 is formed between the supported portion 122 and the embedded portion 125 and the bus bar support portion 14, as in the noise filter 1 of the first embodiment. Therefore, the common mode noise current 502 flowing into the bus bar 12 is divided into a current path passing through the parasitic capacitance component 603 and a current path passing through the parasitic capacitance component 504 of the motor or power supply connected to the power module and grounded. Each flows into the wire and returns to the common mode noise current source 501 via the ground wire.

In the noise filter 1A shown in FIGS. 10 and 11, an LC filter structure is formed by the parasitic capacitance component 603 and the inductance component 701 of the bus bar 12. With this LC filter structure, the common mode noise current 502 can be significantly suppressed.

As described above, according to the noise filter 1A of the present embodiment, common mode noise can be suppressed without using a magnetic core, and therefore, it is manufactured as compared with the noise filter 1C according to the above-mentioned comparative example. The cost can be greatly reduced.

When the noise filter 1A of the present embodiment is applied to the AC filter and used for suppressing the common mode noise current superimposed on the three-phase alternating current output from the power module to the motor as shown in FIG. 12, the first As described in the first embodiment, it is preferable that a capacity of 1 nF or more and 8.5 nF or less is formed between each bus bar 12 and the bus bar support portion 14, respectively.

According to the second embodiment of the present invention described above, the same action and effect as those of the first embodiment are obtained.

(Modification example)
In the first and second embodiments described above, the shape of the bus bar 12 is not limited to that described with reference to FIGS. 1, 2, 10 and 11, respectively. For example, the shapes of the supported portion 122 and the embedded portion 125 can be changed to have a structure as described in the following modification.

FIG. 13 is a cross-sectional view of a noise filter according to a modified example of the present invention. 13 (a), 13 (b), and 13 (c) show cross-sectional views of each modification of the noise filters 1 and 1A in the BB'line shown in FIGS. 1 and 10, respectively. ..

In the modified example shown in FIG. 13 (a), in the supported portion 122, only on one end side in the direction orthogonal to the extending direction of the bus bar 12 (left-right direction in FIG. 13 (a)), in the extending direction of the bus bar 12. An embedded portion 125 formed by bending the bus bar 12 along the line is provided. In the modified example shown in FIG. 13 (b), the bus bar 12 has a prismatic shape in the supported portion 122, so that both ends in a direction orthogonal to the extending direction of the bus bar 12 (left-right direction in FIG. 13 (b)). And the embedded portion 125 are continuously formed between them. In the modified example shown in FIG. 13 (c), the entire supported portion 122 is integrated with the embedded portion 125, and the embedded portion 125 (supported portion 122) is sandwiched between the bus bar support portion 14 via the insulating layer 15. It has a structure.

It should be noted that either of the shapes of the bus bar 12 described in the first and second embodiments and the shape of the bus bar 12 described in the above-described modification can be used alone, or a plurality of shapes may be arbitrarily combined. It can also be used. That is, the bus bar 12 has one of the shapes described in FIGS. 1, 2, 10 and 11, respectively, and the shapes described in FIGS. 13 (a), 13 (b) and 13 (c), respectively. , Or a combination of at least two or more.

Further, a shape other than the shape described in each of the first and second embodiments and the shape described in the above modification may be adopted as the shape of the bus bar 12. Any structure can be adopted as long as a parasitic capacitance component having a desired capacitance value can be formed between the supported portion 122 or the embedded portion 125 and the Basba support portion 14.

According to the modification of the present invention described above, a parasitic capacitance component having a desired capacitance value can be formed between the bus bar 12 and the bus bar support portion 14 without using a Y capacitor.

(Third embodiment)
A third embodiment of the present invention will be described below with reference to FIG. FIG. 14 is a block diagram of a noise filter according to a third embodiment of the present invention.

The noise filter of the present embodiment is for reducing the common mode noise current superimposed on the DC current. For example, a DC power supply that supplies DC power and an AC motor that converts DC power into AC power. It is used by being connected to the power module that outputs. The DC power supply is configured by using, for example, a battery or a converter, and the power module is configured by using a semiconductor element such as an IGBT, MOSFET, SiC, or GaN as the switching element. As shown in FIG. 14, the noise filter 2 of the present embodiment has a filter circuit unit 21, a positive electrode bus bar 22, a negative electrode bus bar 23, a positive voltage input bus bar 24, a negative voltage input bus bar 25, an X capacitor 26, and a

Y capacitor

27, 28. , A smoothing capacitor 29 is provided.

The filter circuit unit 21 has the same configuration as the noise filter 1 described in the first embodiment or the noise filter 1A described in the second embodiment. That is, the filter circuit unit 21 includes a plurality of bus bars 12, a base portion 13, and a bus bar support section 14, and between the supported portion 122 and the embedded portion 125 and the bus bar support section 14 of each bus bar 12. Parasitic capacitance component 603 is formed. The filter circuit unit 21 has a ground terminal 210, and the bus bar support unit 14 is electrically grounded via the ground terminal 210. For example, a metal housing of a power module or a DC power supply or a metal housing of the noise filter 2 itself is used as a frame ground, and the ground terminal 210 is electrically connected to the frame ground to support the bus. The unit 14 can be electrically grounded.

The positive electrode bus bar 22 has a battery-side positive electrode terminal 221 connected to the positive electrode side of the DC power supply and a filter-side positive electrode terminal 222 connected to the filter circuit unit 21. The negative electrode bus bar 23 has a battery-side negative electrode terminal 231 connected to the negative electrode side of the DC power supply and a filter-side negative electrode terminal 232 connected to the filter circuit unit 21. The positive voltage input bus bar 24 has a filter-side positive voltage terminal 241 connected to the filter circuit unit 21 and a positive voltage input terminal 242 connected to the positive voltage input side of the power module. The negative voltage input bus bar 25 has a filter side negative voltage terminal 251 connected to the filter circuit unit 21 and a negative voltage input terminal 252 connected to the negative voltage input side of the power module. By these bus bars connection, the DC voltage output from the DC power supply is input to the power module via the filter circuit unit 21.

The positive voltage terminal 241 on the filter side of the positive voltage input bus bar 24 and the negative voltage terminal 251 on the filter side of the negative voltage input bus bar 25 are connected to one end 121 of the bus bar 12 of the filter circuit unit 21, respectively. Further, the filter-side positive electrode terminal 222 of the positive electrode bus bar 22 and the filter-side negative electrode terminal 232 of the negative electrode bus bar 23 are connected to the other end portion 124 of the bus bar 12 of the filter circuit unit 21, respectively. As a result, when the filter circuit unit 21 has the magnetic core 11, the parasitic capacitance component 603 is formed on the power module side as compared with the magnetic core 11.

The X capacitor 26 is connected between the positive electrode bus bar 22 and the negative electrode bus bar 23. The Y capacitor 27 is connected between the positive electrode bus bar 22 and the ground potential. The Y capacitor 28 is connected between the negative electrode bus bar 23 and the ground potential. The smoothing capacitor 29 is connected between the positive voltage input bus bar 24 and the negative voltage input bus bar 25. The connection of the

Y capacitors

27 and 28 to the ground potential is the same as that of the ground terminal 210 of the filter circuit unit 21, for example, a metal housing of a power module or a DC power supply, or a metal housing of the noise filter 2 itself. It is done by connecting to the housing of. That is, by using these housings electrically connected to the ground potential as the frame ground, one end side of the

Y capacitors

27 and 28 can be electrically grounded, respectively.

The X capacitor 26 smoothes the voltage change (noise) in the DC voltage between the positive electrode bus bar 22 and the negative electrode bus bar 23. The

Y capacitors

27 and 28 smooth the voltage change (noise) between the positive electrode bus bar 22 and the negative electrode bus bar 23 and the ground potential, respectively. The capacitance values of the X-capacitor 26 and the Y-

capacitors

27 and 28 can be determined by arbitrary values according to the frequency band of noise to be suppressed in the DC voltage output from the DC power supply. For example, a capacitive element having a capacitance value of several nF to several μF is used as an X capacitor 26 or a

Y capacitor

27, 28. If necessary, a plurality of capacitive elements may be combined to form the X capacitor 26 and the

Y capacitors

27 and 28. At this time, the capacitance values of the capacitive elements may be the same or different from each other. Further, an X capacitor may be added between the positive voltage input bus bar 24 and the negative voltage input bus bar 25, if necessary.

According to the third embodiment of the present invention described above, each bus bar 12 of the filter circuit unit 21 included in the noise filter 2 converts the DC power supplied from the DC power source into AC power and outputs it to the AC motor. It is connected between the power module and the DC power supply. Further, the noise filter 2 has a positive electrode bus bar 22 connected to the positive electrode side of the DC power supply and a negative electrode bus bar 23 connected to the negative electrode side of the DC power supply, and the bus bar support portion 14 of the filter circuit unit 21 has. It is connected to the ground potential. The noise filter 2 is connected between the Y capacitor 27 connected between the positive electrode bus bar 22 and the ground potential, the Y capacitor 28 connected between the negative electrode bus bar 23 and the ground potential, and between the positive electrode bus bar 22 and the negative electrode bus bar 23. The X-capacitor 26 is provided. Therefore, by using the noise filters described in the first and second embodiments, it is possible to realize a DC filter that reduces the common mode noise current superimposed on the direct current.

(Fourth Embodiment)
A fourth embodiment of the present invention will be described below with reference to FIG. FIG. 15 is a block diagram of a noise filter according to a fourth embodiment of the present invention.

The noise filter of the present embodiment is for reducing the common mode noise current superimposed on the direct current, as in the noise filter 2 described in the third embodiment, and is, for example, a direct current that supplies direct current. It is used by being connected between a power source and a power module that converts DC power into AC power and outputs it to an AC motor. The noise filter 2A of the present embodiment is the same as the noise filter 2 described in the third embodiment, that is, the filter circuit unit 21, the positive electrode bus bar 22, the negative electrode bus bar 23, the positive voltage input bus bar 24, the negative voltage input bus bar 25, and the X capacitor. 26,

Y capacitors

27 and 28, and a smoothing capacitor 29 are provided.

In the noise filter 2A of the present embodiment, the difference from the noise filter 2 described in the third embodiment is the position of the X capacitor 26. Specifically, in the noise filter 2, the X capacitor 26 is connected between the positive electrode bus bar 22 and the negative electrode bus bar 23, whereas in the noise filter 2A of the present embodiment, the X capacitor 26 is a positive voltage input bus bar 24. It is connected between the negative voltage input bus bar 25 and the negative voltage input bus bar 25. As a result, in the X capacitor 26, the voltage change (noise) in the DC voltage between the positive voltage input bus bar 24 and the negative voltage input bus bar 25 can be smoothed.

Also in this embodiment, the capacitance values of the X capacitor 26 and the

Y capacitors

27 and 28 can be determined by arbitrary values according to the frequency band of noise to be suppressed in the DC voltage output from the DC power supply. can. For example, a capacitive element having a capacitance value of several nF to several μF is used as an X capacitor 26 or a

Y capacitor

27, 28. Further, if necessary, a plurality of capacitive elements may be combined to form the X capacitor 26 and the

Y capacitors

27 and 28. At this time, the capacitance values of the capacitive elements may be the same or different from each other. Further, an X capacitor may be added between the positive electrode bus bar 22 and the negative electrode bus bar 23, if necessary.

According to the fourth embodiment of the present invention described above, each bus bar 12 of the filter circuit unit 21 included in the noise filter 2A converts the DC power supplied from the DC power source into AC power and outputs it to the AC motor. It is connected between the power module and the DC power supply. Further, the noise filter 2A has a positive electrode bus bar 22 connected to the positive electrode side of the DC power supply, a negative electrode bus bar 23 connected to the negative electrode side of the DC power supply, and a positive voltage input connected between the positive electrode bus bar 22 and the power module. It has a bus bar 24 and a negative voltage input bus bar 25 connected between the negative electrode bus bar 23 and the power module, and the bus bar support portion 14 of the filter circuit section 21 is connected to the ground potential. The noise filter 2A includes a Y capacitor 27 connected between the positive electrode bus bar 22 and the ground potential, a Y capacitor 28 connected between the negative electrode bus bar 23 and the ground potential, a positive voltage input bus bar 24, and a negative voltage input bus bar 25. It is provided with an X capacitor 26 connected between the two. Since this is done, it is possible to realize a DC filter that reduces the common mode noise current superimposed on the direct current by using the noise filters described in the first and second embodiments as in the third embodiment. ..

(Fifth Embodiment)
A fifth embodiment of the present invention will be described below with reference to FIG. FIG. 16 is a configuration diagram of a motor drive system including a power conversion device according to a fifth embodiment of the present invention.

The motor drive system shown in FIG. 16 is configured by connecting a power conversion device 100, a power supply 200, and a motor 300 to each other. The power conversion device 100 is connected to the power supply 200 via the positive electrode cable 201 and the negative electrode cable 202, and is connected to the motor 300 via a plurality of AC cables 301. This motor drive system is mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle, and is used to drive the electric vehicle using the motor 300 as a drive source.

The power supply 200 is a DC power supply that supplies DC power to the power conversion device 100. For example, in a motor drive system mounted on an electric vehicle such as an electric vehicle or a hybrid vehicle, a high voltage battery of several hundred volts configured by connecting a large number of secondary batteries such as a lithium ion battery may be used as a power source 200. can. Further, in a motor drive system used in a medical device such as an X-ray diagnostic device, a power supply 200 can be obtained by converting a commercial AC power supply into a DC power supply using a rectifier circuit or a converter.

The motor 300 rotates and drives the rotor (not shown) by flowing a current through the coils 302 of each phase provided in the stator (not shown) according to the AC power output from the power conversion device 100. As a result, the motor 300 acts as a load for the power conversion device 100.

The power conversion device 100, the power supply 200, and the motor 300 each have a frame ground. Each frame ground is electrically grounded via a common ground wire.

The power conversion device 100 is the noise filter 2 or the fourth noise filter 2 described in the third embodiment as a DC filter for reducing the common mode noise current superimposed on the direct current flowing through the positive electrode cable 201 and the negative electrode cable 202. It has the noise filter 2A described in the embodiment. Further, as an AC filter, the noise filter 1 described in the first embodiment or the noise filter 1A described in the second embodiment is used as an AC filter in order to reduce the common mode noise current superimposed on the AC current flowing through the AC cable 301. Have.

The power conversion device 100 has a housing 101, a semiconductor module 102, and a control unit 103 in addition to the above DC filters (noise filters 2, 2A) and AC filters (noise filters 1, 1A).

The housing 101 is a metal case that houses each component of the power conversion device 100. Note that FIG. 16 illustrates only the circuits and elements stored in the housing 101 that are necessary in the description of the motor drive system of the present embodiment. The housing 101 is electrically connected to the above-mentioned ground wire and is used as a frame ground of the power conversion device 100. By connecting the DC filter of the power conversion device 100 to the housing 101, the bus bar support portion 14 can be electrically grounded.

The semiconductor module 102 is connected to the DC filter via the positive voltage input bus bar 24 and the negative voltage input bus bar 25, and is further connected to the power supply 200 via the positive electrode cable 201 and the negative electrode cable 202. Similar to FIGS. 14 and 15, a smoothing capacitor 29 is connected between the positive voltage input bus bar 24 and the negative voltage input bus bar 25. The semiconductor module 102 is a power module configured by using semiconductor elements such as IGBTs, MOSFETs, SiC, and GaN as switching elements, and operates according to the control of the control unit 103 to change from DC power to AC power. Perform power conversion. The alternating current generated by this power conversion operation is output from the semiconductor module 102 to the alternating current cable 301 via the AC filter, and is output to the motor 300 through the alternating current cable 301.

The control unit 103 controls the operation of the semiconductor module 102 by controlling the switching operation of each semiconductor element of the semiconductor module 102, and controls the voltage and current of the AC power output from the power conversion device 100 to the motor 300. do. The control unit 103 is configured by using, for example, a microcomputer, and controls the operation of the semiconductor module 102 by executing a predetermined program on the microcomputer. Alternatively, the operation control of the semiconductor module 102 performed by the control unit 103 may be realized by using an integrated circuit such as an LSI, FPGA, or ASIC.

Note that, in the configuration of the motor drive system of FIG. 16, an example in which the power conversion device 100 includes both a DC filter and an AC filter is shown, but the present invention is not limited to this. Only one of the DC filter and the AC filter may be provided, and the other may be omitted. Further, at least one of the DC filter and the AC filter may adopt the structure as described in the noise filter 1C according to the comparative example of FIG.

According to the fifth embodiment of the present invention described above, the power conversion device 100 is supplied from at least one of the noise filters 1, 1A, 2, and 2A, the semiconductor module 102 as a power module, and the power supply 200. It includes a smoothing capacitor 29 that smoothes the DC power to be smoothed, and a control unit 103 that controls the semiconductor module 102. Therefore, the noise current generated in the semiconductor module 102 can be effectively attenuated by the AC filter or DC filter configured by using at least one of the noise filters 1, 1A, 2, and 2A. .. Therefore, the noise leaking from the power converter 100 to the power supply 200 and the motor 300 can be reduced to an appropriate level.

The embodiments and various modifications described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Further, although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects considered within the scope of the technical idea of the present invention are also included within the scope of the present invention.

1,1A, 2,2A: Noise filter 11: Magnetic core 12: Bus bar 13: Base section 14: Bus bar support section 15: Insulation layer 21: Filter circuit section 22: Positive electrode bus bar 23: Negative voltage bus bar 24: Positive voltage input bus bar 25: Negative voltage input bus bar 26: X capacitor 27, 28: Y capacitor 29: Smoothing capacitor 100: Power converter 101: Housing 102: Semiconductor module 103: Control unit 122: Supported part 123: Penetration part 125: Embedded part Part 200: Power supply 300: Motor

Claims

It is a noise filter that suppresses noise superimposed on the current.
With the multiple bus bars through which the current flows,
A bus bar support portion that supports the plurality of bus bars,
An insulating layer arranged between the plurality of bus bars and the bus bar support portion is provided.
The bus bar support portion is a conductor and is
The bus bar has an embedded portion embedded in the bus bar support portion.
The embedded portion is a noise filter that is electrically isolated from the bus bar support portion.
In the noise filter according to claim 1,
Equipped with a magnetic core,
The plurality of bus bars are noise filters that penetrate the magnetic core.
In the noise filter according to claim 1 or 2,
A noise filter in which a capacitance of 1 nF or more and 8.5 nF or less is formed between the plurality of bus bars and the bus bar support portion.
In the noise filter according to claim 1 or 2,
The bus bar has a first shape in which a pair of the embedded portions are formed at both ends in an orthogonal direction orthogonal to the extending direction of the bus bar, and a second shape in which the embedded portions are formed at one end in the orthogonal direction. The shape, the third shape in which the embedded portion is continuously formed between both ends in the orthogonal direction, the fourth shape in which the embedded portion is sandwiched between the bus bar support portions, or the first and first shapes. A noise filter having a shape in which at least two or more of the second, third and fourth shapes are combined.
In the noise filter according to claim 1,
The plurality of bus bars are noise filters connected between a power module that converts DC power supplied from a DC power source into AC power and outputs it to an AC motor, and the AC motor.
In the noise filter according to claim 1,
The plurality of bus bars are noise filters connected between a power module that converts DC power supplied from a DC power source into AC power and outputs it to an AC motor, and the DC power source.
In the noise filter according to claim 6,
The plurality of bus bars have a positive electrode bus bar connected to the positive electrode side of the DC power supply and a negative electrode bus bar connected to the negative electrode side of the DC power supply.
The bus bar support portion is connected to the ground potential and is connected to the ground potential.
A first Y capacitor connected between the positive electrode bus bar and the ground potential,
A second Y capacitor connected between the negative electrode bus bar and the ground potential,
A noise filter comprising an X capacitor connected between the positive electrode bus bar and the negative electrode bus bar.
In the noise filter according to claim 6,
The plurality of bus bars are a positive electrode bus bar connected to the positive electrode side of the DC power supply, a negative electrode bus bar connected to the negative electrode side of the DC power supply, and a positive voltage input connected between the positive electrode bus bar and the power module. It has a bus bar and a negative voltage input bus bar connected between the negative electrode bus bar and the power module.
The bus bar support portion is connected to the ground potential and is connected to the ground potential.
A first Y capacitor connected between the positive electrode bus bar and the ground potential,
A second Y capacitor connected between the negative electrode bus bar and the ground potential,
A noise filter comprising an X capacitor connected between the positive voltage input bus bar and the negative voltage input bus bar.
The noise filter according to any one of claims 5 to 8.
With the power module
A smoothing capacitor that smoothes DC power,
A power conversion device including a control unit that controls the power module.